Our objective is to establish the value of the athymic mouse as an in vivo system for the investigation of human brain tumors. Both human glioma-derived cell lines and freshly transplanted human gliomas will be grown subcutaneously in athymic mice (BALB/c background). Tumors will be serially passaged until growth stabilization occurs and then exposed to a variety of chemotherapeutic agents of potential interest in brain tumor therapy. Quantitative assessment of both growth patterns and chemotherapeutic sensitivities as well as morphological analyses of serially passaged tumors will be made. An attempt will be made to make correlations between a) growth and treatment patterns of the cell lines and their other phenotypic traits, and b) growth and treatment patterns of the transplants with behavior of the tumors in their original hosts.